Hi Reversal, I think it is a good idea to leave your sister alone and work on the topic with a professional to sort it out for yourself. It might turn out your sister needs qualified help, and it would be the responsibility of your counselor, therapist or whatever to make sure she gets it. This is none of your business, unless you are a superhero.
In my opinion it was a mistake to play that games with your little sister, too much inbalance of power. You crossed a red line, but that is what children do. The time will come when she is ready to tell her part of the story.
My sister is 4 years ahead. I hated her for really good reasons when she left home. Our relation changed when she was out. We were no longer forced together, free to choose each other. I had good times with her. One day I told her my part and she understood, apologized and even compensated. Way to go.